PROJECT SUMMARY Daily free sugar intake today as well: on average, children is considered too high not only for teens and adults, but among infants and toddlers exceed the adult daily limit by two years of age. Yet, rigorous evidence on the long- term health impacts of this early childhood exposure is limited and the causal pathways through which early- childhood nutrition has long-lasting effects are poorly understood. One possibility is physiological changes with lasting effects on disease risks. Another is habit formation, as the preference for sweetness is shaped by exposure to a sugar-rich diet early in life and its excessive consumption that may then persist into adulthood. The scarcity of empirical evidence is not that surprising. Evaluating these relationships empirically is challenging in large part due to the lack of high-quality data that span a period that is sufficiently long, but also because of selection concerns. Because random assignment of sugar-rich diet is often infeasible, evidence from natural experiments is needed. The goal of this study is to exploit a unique natural experiment that provides plausibly exogenous variation in exposure to sugar and sweets early in life in order to evaluate the long-term causal effects on diet and health in adulthood. The natural experiment is the rationing of sugar and sweets in the UK between January 1940 and February 1953, which likely induced variation in the diet and health of today's older adults. Using a regression discontinuity design, we assume that cohorts born right before and after February 1953 when the rationing ended are similar, except in their exposure to sugar and sweets early in life. Our specific aims are to: Aim 1: Examine how intake of sweets early in life influences diet and health in adulthood. Aim 1a: Assess cohort differences in daily intake of total calories, food groups (e.g., savory and sweet snacks, fruits, vegetables, meats, desserts), sugar and other nutrients (e.g., free and intrinsic sugars, proteins, fats). Aim 1b: Assess cohort differences in mortality, morbidity, and in/outpatient health care visits for diet-related disease, such as obesity, diabetes, disability, hypertension, stroke, heart attack, arthritis, and cancer. Aim 2: Examine cohort differences in occupation, retirement age, earnings, assets and wealth with the goal of understanding the extent to which health differences among today's older adults contribute to these outcomes. Aim 3: Examine whether the long-term effects vary by exposure to rationing Aim 4: Examine if sex and socio-economic characteristics in childhood moderate the impact of early exposure to sweets on adult diet, health and economic well-being. The findings will, at a minimum, provide a new reference for guidelines on free sugar intake for children below two years of age and their long-term impact, as well as inform early obesity prevention efforts. Since both UK and the US have comparable, world's highest intake of free sugar and almost identical current and projected prevalence in obesity and related chronic disease, our findings will be incredibly relevant and valuable to the US.